Question: Simplify the following expression: $y = \dfrac{a^2 - 2a - 24}{a - 6} $
Solution: First factor the polynomial in the numerator. $ a^2 - 2a - 24 = (a - 6)(a + 4) $ So we can rewrite the expression as: $y = \dfrac{(a - 6)(a + 4)}{a - 6} $ We can divide the numerator and denominator by $(a - 6)$ on condition that $a \neq 6$ Therefore $y = a + 4; a \neq 6$